\begin{tikzpicture}
    \tkzDefPoints{0/0/B, 3.5/0/D, 2.8/2.5/A}
    \tkzInterLC(B,D)(A,D)  \tkzGetFirstPoint{C}

    \tkzDrawPolygon(A,B,D)
    \tkzDrawSegments(A,C)
    \tkzMarkSegments[mark=|](A,C  A,D)
    \tkzLabelPoints[above](A)
    \tkzLabelPoints[below](B,C,D)
\end{tikzpicture}

